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Saturday, December 25, 2010

Nissan Leaf As An Emergency Power Source

While doing a test drive I discovered that the Nissan Leaf has an ordinary 12 volt lead acid battery under the hood. It charges off of the main battery pack, which is several hundred volts. In other words, because you don't need to run an engine to turn an alternator to charge the 12 volt battery, it shouldn't go dead in just a few hours if you use it to run something like your laptop while car camping (which actually happened to me last summer with our Prius). And if I'm wrong, it wouldn't take much for Nissan to make it so with a tweak to the operation software and lead acid battery charging hardware.

This feature could make the Leaf into an ideal emergency power source should a wind storm knock out power to your home. All you have to do is connect a power converter like the one shown above ($95.00) to your 12 volt battery and run extension cords from it to lights or appliances.

In the past month there have been two major power outages in my neck of the woods caused by bad weather. Some friends of ours had to live three days without electricity in subzero weather.

As with any emergency power backup system, you would have to be careful about how much current you used. The inverter above is rated to about 1000 watts. In our house I would use it to intermittently run our gas furnace blower motor, which draws about 300 watts, and various appliances, including flashlights, a laptop (and modem) for news etc, and electric bike batteries, which can also power large flashlights.

Depending on outside air temperature, I might just move food outside rather than run a refrigerator.

With 24 thousand watt hours in the Leaf battery, you could get by for weeks if you were frugal with power use. You might not want to drive the Leaf much until the power is restored just in case.

It doesn't take much imagination to go from the above scenario to one where we all share our batteries on a smart grid to stabilize renewable energy sources like wind and solar.

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Monday, December 13, 2010

The EPA's outrageous lie?

Photo from Wikipedia

Back in September I wrote a rebuttal titled:

Securities Lawyer Mocks Electric Vehicle Enthusiasts--Gets Mocked Back

Here I rebut that author's latest critique of electric cars which he titled Alice in EVland Part II; The Hall Of Mirrors.

Instead of mocking electric car proponents, he questions their integrity:

Mark Twain reportedly said that "Figures don't lie, but liars figure." Truer words were never spoken.

Both stickers [for the Leaf and Volt] were heralded as the dawn of a new age in transportation [which isn't true]. Unfortunately, they were outrageous lies that account for the distance a car can travel on a kilowatt-hour of electricity but ignore the energy needed to make a kilowatt-hour of electricity in the first place. [my emphasis]

What got this securities lawyer's boxers in a bind this time? Well, apparently it was the revelation that the Leaf will use about ten percent more life cycle energy than a Prius. Not to suggest that this is his revelation. He's just parroting other internet blog articles (without attribution) that pointed this out last month when the EPA first released its new mileage sticker for electric cars:

He thinks he has stumbled onto something new and that the EPA sticker is trying to deceive consumers because it does not account for life cycle energy use. Here's an article I wrote on equivalent MPG back in August of 2009.

However, every study I've read on this subject for the last several years has pointed out the fact that electric cars use slightly more life cycle energy (and produce slightly more GHG) than an equivalent hybrid when their electricity comes from non-renewable sources like coal. But, they have also pointed out that electric cars use far less life cycle energy and produce far less GHG than the average car, of which there are over 300 million in this country.

What is life cycle energy? Well, about 60-70 percent of the energy in the coal used to make electricity is lost. Only about 30-40 percent of it gets into the wires as electricity. More energy is lost in the wires, the charger, and the electric motor.

Even though and electric car is three times more efficient than a normal car, in the end, the Leaf will actually use about 10 percent more total energy than the most efficient car ever mass produced, the Prius, but about half the total energy of the average car.

EPA mileage stickers have never used life cycle energy. That would be complicated, and confusing. For example, it takes about 20 percent more oil to make diesel fuel than gasoline. So, using life cycle energy, you would have to reduce that mileage on the Jetta sticker 20 percent, but the diesel Jetta will still go a lot further on a gallon of fuel than the gasoline Jetta, in large part because diesel engines are more efficient.

Is that what consumers are interested in or do they want to compare how efficiently different cars use the energy stored in their tanks or batteries? That is why the EPA came up with MPGe (miles per gallon equivalent).

The sticker also rates GHG emissions out of the tail pipe, of which electric cars have none. Life cycle green house gas emissions are not part of the deal either. If your car gets its electricity from a coal plant, it is in theory increasing GHG emissions more than a Prius. In reality, until there are enough electric cars to be noticed, the power plant will not be throwing any more coal on the fire and if you have solar, or hydro, or wind, or nuclear making your power, your life cycle GHG is going to be lower than a Prius. So again, why try to convey that kind of complexity on a window sticker?

You have to start somewhere and consumers can start with a low emission, highly efficient vehicle. Cleaning up power supplies is happening in parallel.

Not to say that total energy consumed (from coal mine to wheel turning) isn't important. I'm saying it is not the only metric that's important.

A solar panel only captures about 8 percent of the energy that strikes it. Solar energy is far less efficient than coal but who cares if we have to waste 92 percent of the sun that hits it to get solar power? A similar argument holds for nuclear power (and lets face it, solar collectors are essentially fusion powered).

If we can displace coal and natural gas with solar, wind, hydro, geothermal, and nuclear, we will have a carbon and oil free transportation system and it does not matter if that takes more overall energy use. It's an engineering trade off that's well worth it.

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